Philadelphia City Council President Darrell L. Clarke knows the time to make a decision is nigh.

Some have suggested that he could wait as long as February. He shakes his head vigorously when told that.

"No, that would not be fair," he said. "That would be a little selfish. You have to tell people something."

Now, perhaps?

He shakes his head again.

"I have to say one way or another for a lot of reasons, and that point is coming soon," he said. "Real soon."

Some day in the near future, then, Clarke will end the speculation and announce whether he intends to run for mayor of Philadelphia. Just not yet.

The question of his intentions has loomed increasingly large in recent weeks as the race for the 2015 Democratic nomination has finally begun to gather a field.

Clarke's decision will ultimately help determine the shape of that field. His indecision has already driven one potential candidate, City Controller Alan Butkovitz, from the race. Butkovitz was counting on the support of key labor leaders such as John "Johnny Doc" Dougherty of the electrical workers, whose first choice remains Clarke. With Clarke undecided, that support remains on the sidelines.

The belief among his champions is that the Council president would enter the race as the front-runner, easily outdistancing a May 19 Democratic primary field that now includes former District Attorney Lynne M. Abraham; Terry Gillen, former head of the Redevelopment Authority; Ken Trujillo, a former city solicitor; and State Sen. Anthony Hardy Williams.

That might be a faulty assumption, said Sam Katz, a three-time Republican mayoral candidate and still a sharp read when it comes to local politics.

Katz recalled that similar presumptions were made in 2007 about some mayoral candidates - U.S. Rep. Chaka Fattah (D., Phila.) comes to mind - only to be disproved with the election of Michael Nutter, who was, in many ways, the least-expected winner.

As Katz sees it, Clarke's Hamlet routine itself might argue against his candidacy.

"His indecision is the thing he needs to look [at] most," said Katz, who hasn't flatly ruled out running next fall as an independent. "The fire has to burn really hot in the belly if you want this. If you are going at this with any reservations, voters are going to sense that."

There certainly seemed to be more hesitation than heat last week when Clarke sat down to talk about the mayor's race and his ultimate role in it. In fact, in many ways, he showed more passion for the job he has now than the one held by Mayor Nutter.

"I like being Council president. I like my colleagues. I really enjoy the environment around here," he said. "You can see that most of the votes tend to be unanimous or close to that. It is obvious that we have established a camaraderie in City Council.

". . . I certainly have aspirations as to what I want to see for the city. . . . I don't think it is so important to be mayor. I think it is important to push that agenda."

So does that mean he won't run?

"I don't know what I ultimately will do," he said, before ticking off myriad issues before Council that have occupied his time, including the fate of the Philadelphia Gas Works. "I woke up at 5 a.m. today - guess what I was thinking about? PGW."

The Gas Works is a big issue, in part, because of him: He and the Council have all but spiked Nutter's plan to sell it.

That is not to suggest that the mayor's race is far from Clarke's thoughts.

"Are there a lot of people who want me to run? More than people realize," he said. "Is it flattering to be mentioned in that way? Sure, I'm human. Do I spend my waking days thinking about it? Only when every other person asks me if I'm going to run for mayor."

So is he?

"I've been consistent. I say I want to be the best Council president I can be."

There he is, then, "the Sphinx of City Hall," a label affixed by some who say he has mastered the art of revealing little while saying much.

"Darrell's gift is that he is like lyrical music," said one officeholder who spoke on condition of anonymity and who has had an admittedly frustrating relationship with Clarke. "He can make you feel something he didn't say."

Told that some find him inscrutable, he offered his own description.

"I'm even-keeled," he said. "And it works for me and it works for the people I work with. People don't want to see a leader get emotional. People say to me, 'Man, all the pressure you're under.' Are there times maybe my stomach is turning? Probably. But do I need to show it?"

He certainly seemed cool as he spoke. His lanky frame casually draping his chair, Clarke had the aw-shucks demeanor of an easygoing neighborhood kid who, at 62, seems even yet a little surprised to find himself in the second-most-powerful seat in city government.

"It is rare that you get an opportunity to be in a position to effect change at this level," he said. "For a guy who grew up in this city, this is special. You actually have the opportunity to do things for all the people. That is what intrigues me about this job."

And the mayor's office?

"What I would do as mayor would be the same thing I do as Council president," he said, a nod to his focus on boosting the city's lesser neighborhoods as opposed its more glittering center.

"You can't have an environment where you are talking about a $50 million front yard for City Hall" - translation: Dilworth Park - "but you ignore a bridge on Montgomery Avenue that should be shut down because it is not safe."

Forty minutes into the interview, there was still no hint of his plans.

"There are lot of things I need to consider. Right now the only thing I've been thinking about is the PGW issue," he said. "I realize at some point, if I am interested, I have to tell people. And if I definitely rule it out, I have to tell people. That clock is ticking very quickly."

Or so he says.